The present invention relates generally to an apparatus for reducing or eliminating blow back into an intake manifold in an internal combustion engine and a method of assembling said apparatus. More specifically, the invention relates to a novelly constructed reed valve assembly for preventing engine efficiency-robbing turbulence from forming in a manifold in an internal combustion engine.
The construction and operation of internal combustion engines are well known in the relevant art. During the cyclic operation of such an engine, a mixture of air and fuel is delivered from an intake manifold to a cylinder, having an oscillating piston, through an intake valve for combustion. The intake valve is located in the air/fuel mixture flow path between the manifold and the cylinder.
At the beginning of the engine's cycle in it's simplest form, the piston is located adjacent a top of the cylinder. The intake valve is opened, and the piston begins its downward stroke within the cylinder. The downward movement of the piston generates a reduced or negative pressure in the cylinder. Simultaneously, a mixture of air and fuel is injected, under an increased or positive pressure, into the intake manifold. The pressure differential between the intake manifold and the cylinder causes the air/fuel mixture to move, or be sucked into the cylinder. Once the piston reaches the bottom of the cylinder, the piston reverses its travel and begins its upward stroke towards the top of the cylinder (i.e. the compression stroke). The intake valve is simultaneously closed, and the air/fuel mixture is compressed between the top of the cylinder and the advancing piston. Once the piston reaches the top of the cylinder, the air/fuel mixture is ignited, and the combustion of the mixture drives the piston downwards, thereby generating power in the engine. Now, the exhaust stroke of the piston begins, wherein the exhaust valve opens and the piston moves upwardly to force the exhaust gases from the cylinder out through the exhaust valve. Upon completion of the exhaust stroke, the piston is in position to repeat the cycle.
In theory, internal combustion engines are to function in generally the above-discussed fashion. However, in practice, this does not always occur precisely as intended as a back pressure may be generated in the intake manifold which can cause turbulence in the intake manifold, and which can compromise the efficiency of the engine, especially since multiple cylinders are often associated with a single manifold. In practice, engine behavior during normal operation, at all speeds within normal operating ranges, is precisely controlled by mechanical, electrical, and fluid dynamic means. It is common practice to adjust intake and exhaust valve timing such that at higher engine speeds the momentum of the exiting exhaust gases can be taken advantage of. This momentum is utilized to provide a scavenging effect to the cylinder while dynamically drawing in additional air/fuel charge. To accomplish this, engine/cam/induction/exhaust system designers open the intake valve prior to the piston reaching top dead center. At this point the exhaust valve is also slightly open. This situation is commonly referred to as overlap, a point at which the exhaust valve lift curve overlaps the intake valve lift curve, that is, both valves are in the open position. At higher engine speeds (those which produce sufficient exhaust gas momentum) the high speed exhaust charge traveling down the manifold will produce a negative pressure in the cylinder. This draws the intake charge into the cylinder even though at the beginning of this scavenging and charging the piston is still moving up. Note that due to the harmonic motion generated by the slider crank mechanism which attaches the piston to the crank shaft, that piston velocity is approaching 0.0 at this point. Engine designs can be optimized to take advantage of this effect to produce additional power in the desired RPM range due to the resulting denser intake charge. This approach is known to produce additional power within a defined engine speed range. However, at lower engine speeds exhaust gas velocity is insufficient to produce the desired effect. Under these circumstances, exhaust gases are forced back into the intake system causing turbulance and disturbing charge density, a condition commonly referred to as "blow back." The result is reduced power at lower engine speeds and rough idle. The reed valve assembly of the present invention is beneficial in reducing the blow back and turbulance mentioned above. With a reed valve device in the system, one can achieve the benefits of cylinder scavenging at higher engine speeds without the performance sacrifice at lower engine speeds and rough idle.
It is known to employ a reed valve assembly in the intake manifold of an internal combustion engine to prevent "blow-back" or turbulence in the manifold. The present invention provides an improved reed valve construction as well as a method of assembling the improved reed valve.